The invention relates generally to botanical extracts and, more specifically, to extracts of passion fruit (Passiflora sp.), including particularly extracts of the skin of passion fruit, and the use of the extracts for food, nutraceutical, and medical applications.
Hypertension, or a blood pressure higher than 140/90 mm Hg, is the most common risk factor for cardiovascular and cerebrovascular morbidity and mortality. In the United States, high blood pressure is responsible for 40,000 deaths annually, while being the most modifiable risk factor for stroke. Hypertension affects about one in four adults, or almost 50 million people in the United States.
A Framingham study showed that as people aged from 30 to 65 years, their blood pressure increased an average 20 mm Hg systolic and 10 mm Hg diastolic pressure, with systolic blood pressure continuing to rise up to age 90.
While higher blood pressure increases the likelihood of a cardiovascular event, hypertension is not often well controlled and too few patients are adequately treated. Epidemiologic studies predict that reduction of the systemic blood pressure by the amount usually achieved in major clinical trials could reduce cerebrovascular events by 42% and cardiac events by 24%
Hypertension is frequently treated non-specifically, resulting in a large number of minor side-effects, and a relatively high rate of non- or inadequate treatment. Thus, the search for new treatments for hypertension remains ongoing.
Therapies derived from natural products are well known. It has been established that certain flavonoids have a beneficial effect on hypertension. For example, a bark extract from the French maritime pine (Pinus pinaster), which contains a mixture of flavonoids, decreases systolic blood pressure when taken orally by mildly hypertensive patients.
Nitric oxide is an important molecular regulator of blood pressure. Nitric oxide is a potent vasodilator. It inhibits platelet activation, limits leukocyte adhesion to the endothelium, and regulates myocardiocontractility. Synthesis of nitric oxide catalyzed by nitric oxide synthase (NOS) occurs in the vascular endothelium while the production of nitric oxide involving inducible nitric oxide synthase (iNOS) is associated with immune function. However, small amounts of nitric oxide produced by another NOS, epithelial nitric oxide synthase (eNOS), have a cytoprotective effect and vasodilation action on the cardiovascular system.
Peroxynitrite is a potentially damaging oxidant, formed from nitric oxide (NO+O2 ONOO−). Peroxynitrite can give rise to lipid peroxidation, protein nitration, DNA single-strand breakage, and guanidine nitration.
It has been shown that the flavonoids quercetin and kaempferol inhibit NOLA-dependent spontaneous aortic ring contraction in spontaneously hypertensive rat (SHR) cells in vitro. NOLA is a nitric oxide synthase inhibitor. Large dose acetylcholine-induced vascular contraction can also be inhibited by antioxidative flavonoids such as quercetin, kaempferol, rutin, and esculetin. Inhibition of vascular smooth muscle contraction should lead to lower blood pressure.
In addition, the effects of flavonoids on immune function are controversial. Catechin enhances proliferation of lymphocytes and antibody production, while it exerts an inhibitory effect at high concentration. Some studies show that flavonoids enhance NK cell activity, while other studies show that flavonoids have no effect. Quercetin seems to inhibit non-specific immunological responses and exerts an anti-inflammatory action.
Passion fruit (Passiflora edulis) is a subtropical or tropical plant with a vigorous climbing character, growing to 20 ft. The purple passion fruit is native from southern Brazil through Paraguay to northern Argentina. Its fruit is nearly round or ovoid, 1.5 to 3 inches wide, with a tough, smooth and waxy rind.
In a search for bioactive constituents of passion fruit, it has now surprisingly been found that a passion fruit extract lowers systolic blood pressure in spontaneously hypertensive rats (SHR), and decreases nitric oxide production from iNOS, thus improving endothelial dysfunction in SHR. It is therefore also envisaged that the passion fruit extract will exhibit antioxidant properties.
It is therefore an object of the invention to provide an extract of passion fruit which exhibits therapeutic effects against hypertension, and diseases associated with hypertension, and which is hepatoprotective, or at least to provide a useful choice.